Public water system · MI0001370
ActiveChelsea
At a glance
Chelsea (PWSID MI0001370) is an active community water system in Washtenaw County, Michigan. It reports serving 5,474 people through 2,000 service connections. Its primary water source is groundwater, and EPA lists it as owned by a local government. EPA's records list 5 violations for this system; 4 are health-based, and the most recent began in July 2005.
Dataset updated . Source: EPA SDWIS/ECHO public records.
Population served
5,474
Service connections
2,000
Primary source
GW
Groundwater
System type
CWS
Community water system
System record
How does Chelsea compare with other water systems in Washtenaw County?
By EPA's size categories, Chelsea is a medium system (3,301 to 10,000 people). Washtenaw County has 262 active public water systems. Its population served is about 4.8 times the county average of 1,147 people per system, and accounts for 1.8% of the 300,406 people reported by systems filed under the county. Across Michigan, the 10,599 active systems average 847 people each. Nationally, the average active community water system reports serving 6,703 people, so Chelsea is about 18% below that figure.
What does “community water system” mean?
A community water system serves at least 15 connections used by year-round residents, or regularly serves at least 25 year-round residents. Homes, apartments and mobile-home parks are served by these. Michigan has 1,332 active community water systems, 13% of the state's 10,599 active systems. Groundwater means the system draws its water from wells or springs fed by underground aquifers. 10,214 Michigan systems (96%) list groundwater as their primary source.
Who owns and regulates Chelsea?
EPA lists Chelsea as owned by a local government. The MI state drinking water program is its primacy agency, the regulator with primary enforcement responsibility for the system under the Safe Drinking Water Act. 16 of the 262 active systems in Washtenaw County (6.1%) are also owned by a local government.
Does Chelsea have drinking water violations?
EPA's records list 5 violations for this system; 4 are health-based, and the most recent began in July 2005. The violations listed here began between October 1993 and July 2005. By type: 3 contaminant level above the legal limit, 1 public notice, recordkeeping or other and 1 required treatment not met. The contaminant or rule involved most often is Total coliform bacteria (TCR) (3 of them). EPA lists 5 as resolved. Resolved means at least one resolving action is on record: the system returned to compliance, the rule no longer applies, or no further action was needed.
| Began | Violation | Contaminant or rule | Health-based | Status |
|---|---|---|---|---|
| 2005-07-01 | Public notice, recordkeeping or otherConsumer Confidence Report Complete Failure to Report · code 71 | Consumer Confidence Rulecode 7000 | No | Resolved |
| 2003-06-01 | Required treatment not metTreatment Techniques · code 07 | Acrylamidecode 2265 | Yes | Resolved |
| 1996-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1995-08-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
| 1993-10-01 | Contaminant level above the legal limitMaximum Contaminant Level Violation, Monthly (TCR) · code 22 | Total coliform bacteria (TCR)code 3100 | Yes | Resolved |
All 5 violations in EPA's records, newest first.Labels and codes come from EPA's SDWIS reference tables. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found. "Health-based" marks violations of a legal limit or required treatment.
Chelsea: frequently asked questions
Who runs Chelsea?
Chelsea (PWSID MI0001370) is a community water system owned by a local government. It is regulated by the MI state drinking water program.
How many people does Chelsea serve?
Chelsea reports serving 5,474 people through 2,000 service connections in Washtenaw County, Michigan.
Where does Chelsea get its water?
EPA SDWIS lists this system's primary water source as groundwater. Groundwater means the system draws its water from wells or springs fed by underground aquifers.
Does Chelsea have any drinking water violations?
EPA's records list 5 violations for this system; 4 are health-based, and the most recent began in July 2005. A monitoring or reporting violation means a required test or report was missed or late; it does not by itself mean a contaminant was found.
Is Chelsea's water safe to drink?
AquaCensus shows EPA compliance records, not current water test results, so it cannot say whether the water is safe at a given moment. EPA's records list 5 violations for this system; 4 are health-based, and the most recent began in July 2005. For current results, consult the system's annual water quality report, EPA ECHO, or the MI state drinking water program.
Where can I find Chelsea's water quality report?
As a community water system, Chelsea must deliver an annual water quality report, called a Consumer Confidence Report, to its customers by July 1 each year, covering the previous calendar year. The system can provide a copy on request.
Other water systems in Washtenaw County
| Water system | County | Population served | Type | Source |
|---|---|---|---|---|
| Ann Arbor | Washtenaw | 123,851 | Community | Surface water |
| Ypsilanti Community Utility Authority | Washtenaw | 53,988 | Community | Purchased surface water |
| Pittsfield Township | Washtenaw | 24,500 | Community | Purchased surface water |
| Saline | Washtenaw | 9,158 | Community | Groundwater |
| Scio Township | Washtenaw | 8,500 | Community | Purchased surface water |
| Milan | Washtenaw | 7,363 | Community | Groundwater |
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About this data
Source: U.S. EPA Safe Drinking Water Information System (SDWIS) and SDWA violation records, via EPA ECHO, as published October 1, 2026 — AquaCensus refreshes it quarterly. See the methodology for how records are matched, cleaned and scored.
Cite as: AquaCensus, “Chelsea, PWSID MI0001370, Michigan”, https://aquacensus.com/water-systems/michigan/chelsea-mi0001370 (data as of October 1, 2026).